PH CONTROL METHOD FOR CLEANING DRAIN FOR WET ELECTRICAL DUST COLLECTOR

PURPOSE:To retain pH of cleaned drain to the given value without the delay in time even when the load of a source of gas to be treated such as the boiler load or the like is varied in a wet cylindrical dust collector used for the cleaning of an electrode by circulating the cleaning drain of the electrode. CONSTITUTION:In a wet electrical dust collector used for cleaning an electrode 1 by treating gas containing SO2 and SO3 and circulating cleaning drain for the electrode 1, the injection amount of caustic soda 10 into the cleaning drain is adjusted based on pH of the cleaning drain, and also the injection amount of caustic soda 10 into the cleaning drain is adjusted based on the variation of load of the source of gas to be treated such as the boiler load to retain the pH of cleaning drain at the given value without the delay in time to the variation of the amount of gas to be treated and the SO2 and SO3 concentration in the exhaust gas.